HP-86A screen calibration problem

[Dave Britten]

Looks like the typical results of a monitor trying to auto adjust but not being able to figure out where the edges of the image are. Either manually adjust the image size and position using the monitor's controls, or write a small program that fills the entire screen with a black/white checkerboard pattern, alternating every pixel. That usually helps the auto-adjust routine figure out the size and clock (even with modern computers using an analog VGA connection).